Metabolism of Intraperitoneally Injected Serum Protein. ∗

Abstract

Two groups of 10 albino rats with identical average body weights were selected. For 2 days they were given no food. On the morning and evening of each day 12 cc of 6.4% dextrose in 0.9% sodium chloride was injected into the peritoneal cavities of the controls while to the experimental group an injection of 12 cc of freshly separated serum obtained from normal rats was given. Both groups were anesthetized 48 hours after the first injection and 18 hours after the last. All the blood that could be obtained from the cut abdominal aorta while the heart was still beating was centrifuged at high speed for half an hour and the serum separated from the clot. The quantity thus drawn represents about 75% of the total blood volume. The liver, kidneys and heart were then removed, weighed and prepared for the protein determinations. The contents of the alimentary tract were removed after boiling in 0.5 M acetate buffer at pH 5. and the protein content of the tract determined with the carcass. 1 In the experimental group the abdominal cavities contained on an average nearly 5 cc of a fluid that had a somewhat higher protein concentration than the serum that had been injected. This fluid was collected and its protein is not included in the total protein given in Table I.

Since the original body weights of the two groups were identical the quantities found after 48 hours may be directly compared. It is evident that in all the organs examined serum injection is associated with a higher protein content than is found after dextrose injection. But the only important question is whether this greater protein content is a part of the rat's protein or is only the serum protein that we had injected.